Blower



April 12, 1960 K. L. WALKER BLOWER 2 Sheets-Sheet 1|.

Filed Sept. 13, 19s? INVENTOR. Ampfiu L. WALKER.

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April 12, 1960 K. L. WALKER BLOWER 2 Sheets-Sheet 2 Filed Sept. 15, 1957 khi o 4 Mkx $35K 20 53K kwk Om INVENTOR. Kev/0191.4 L W/u KER.

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United States Patent F BLOWER Kendall L. Walker, Manchester, Conn., assignor to The Spencer Turbine Company, Hartford, Conn., a corporation of Connecticut Application September 13, 1957, Serial No. 683,892

3 Claims. (Cl. 230-129) This invention relates to a blower and more particularly to an air blower, or compressor, of the centrifugal or turbo type having one or more impellers for moving air therethrough.

It is well known by those skilled in the art that, in the operation of conventional multiple stage blowers of this type, less than maximum air pressure is produced within the blower when there is a low, or no air demand, due to the resistance against the movement of the air through the impellers. As the demand for air increases and the resistance decreases, the volume of air moved by the blower increases and the pressure increases with the volume until the volume reaches between 40% and 50% of the maximum volume capacity of the blower. Then, as the volume continues to increase, the pressure will drop.

When a sudden drop in air demand occurs in a system with such a conventional blower, the resultant drop in air pressure within the blower to below maximum momentarily causes a condition in which the air pressure in the delivery pipes of the system is higher than in the blower itself. This causes a backing up of pressure from the pipes into the blower which unbalances the pressure in the system and thereby causes objectionable surging and pulsation within the system. Also, when a plurality of such blowers are connected in parallel to a common header, there is an uneven distribution of flow among them which causes one blower to become overloaded before another blower will share the load do manded by the system.

It is therefore highly desirable in such blowers to eliminate the pressure deficiency at low air demand so as to increase the efliciency of the blowers and prevent, or minimize such surge and pulsation and thereby greatly improve the operation of such blowers.

An object of the present invention, therefore, is to provide a multi-stage centrifugal type blower having ever decreasing pressure characteristics, ranging from no air delivery to the full blower rating and beyond, and which is capable of producing maximum air pressure at no air delivery whereby the air pressure will be decreased as the volume of air moved by the blower is increased throughout the entire range of the blower.

A further object of this invention is the provision of a booster fan or stage in a multiple stage centrifugal blower in which the pressure will increase at no air delivery to better than the maximum pressure obtainable during air delivery so that the pressure produced by the blower will always increase as the demand decreases.

A still further object of the invention is to provide highly eflicient means for controlling the volume of air delivered by the blower in accordance with the demand placed thereon.

Further objects and advantages of this invention will be more clearly understood from the following description and the accompanying drawings in which:

Fig. 1 is a sectional end view, on line 1-1 of Fig. 2, of an air blower embodying the present invention.

2,932,444 Patented Apr. 12, 1960 Fig. 2 is a sectional side view on line 2-2 of Fig. 1.

Fig. 3 shows a graphic curve illustrating the operation of a blower embodying the present invention.

In the embodiment illustrated in the drawings, my improved air blower includes a casing 5 having a front end plate 6 with an inlet 7 therein and a rear end plate 8. Between the said front and rear end plates, there is contained a series of partitions 9-9 defining compression chambers 10 each of which includes an air passage 11 leading to an inlet opening 12 of the next compression chamber and so on. Within each of the said air passages 11 there is provided a series of vanes 13 which guides the air as it is moved toward the said opening 12.

A motor 14 is mounted upon the rear of the blower and has a driving shaft 15 which preferably extends throughout the entire length of the blower and has mounted thereon an impeller 16 for each of the compression chambers.

In the embodiment shown, three compression chambers and three impellers are provided. These compression chambers, combined, form the high volume, low pressure section of the blower which is herein called the primary stage and includes a main high volume outlet 17-17. Next to the last pressure chamber 16, there is provided a partition 18 which is preferably double walled and spaced from a partition 19 that is disposed next to the main high volume outlet 17. Between the said partitions 18 and 19 there is provided a restricted air passage 20 having guide vanes 21 therein leading to the inlet opening 22 of a high pressure booster chamber 23 in a second section, or high pressure stage, of the blower which is herein called the booster stage, and is provided between the said partition 19 and the plate 24 at the high pressure end of the blower. Within the said booster chamber 23, there is provided an impeller or booster fan 25 which is smaller than the impellers 16, as shown. The said booster fan receives the air from the passage 20 and forces it radially into the booster chamber 23 from which it is delivered through the high pressure outlet 26 in the casing 5.

An outlet pipe 27 is provided on a tangent with the circumference of the case 5 and encompasses both of the outlet openings 17 and 26. A partition 28 is provided in said outlet pipe 27 between the openings 17 and 26 to divide the lower portion of the pipe into high pressure and low pressure outlet passages 29 and 30, respectively. A valve 31 is preferably pivotally mounted upon the partition 28 and is normally biased by a spring 32 into position to close the passage 30.

In the operation of the embodiment above described, when the motor 14 is energized, air will be drawn inwardly through the inlet 7 into the first impeller 16 and will be moved radially thereby into the first compression chamber 10 of the primary stage. From this compression chamber it will pass through the passage 11 and the inlet 12 into the next compression chamber from which it will then be likewise moved into the next compression chamber of the primary stage and then through the outlet opening 17. At low air delivery, the valve 31 will remain closed, under the influence of the pressure in the passage 29, and the said air will move into the restricted passage 20 and the inlet 22 and through the impeller 25 into the high pressure, or booster, chamber 23 from which it will pass outwardly through the high pressure outlet 26 and into the high pressure passage 29 in the outlet pipe 27.

High pressure which is applied to the high pressure side of the valve 31, during low air demand, will move the said valve toward closed position. The air delivery through the opening 17 is then resisted by the valve and this will simply reduce the movement of the air by the first stage impellers to only the volume of air which can pass through the restricted passage 20 into the booster stage. When the demand for air increases, the pressure in the passage 29 decreases and this allows the valve 31 to open and substantially the full volume of air from the first stage. will move through the passage 30 and past the valve 31 vrhile a small portion of said air will continue to pass hrough the booster stage of the blower.

The operation of my improved fan will be more clearly understood from the graphic curve, illustrated in Fig. 3 of the drawings, from which it will be seen that at zero andlow volume the pressure of a standard or conventional type multi-stage blower is less than the maximum pressure indicated by said curve. As the volume increases, the pressure rises until approximately fifty percent ojf rated capacity is reached. In a blower which is provided with a booster tan, in accordance with this invention, the pressure delivered by the blower is at the highest point at. no air delivery and gradually decreases as he volume increases. Therefore, during the Operation of a system having my improved. blower ther in, the pressure within the blower itself is always higher han in any oth r p t of th syst m nd the backing- P t pressure into said blow r an resul ing u ge an pulsation is thereby prevented.

Blowers constructed in accordance with the above described invention re parti larly adapted for use to s pply air to such as oil and gas fired equipment, foundry cupolas and the like, in which the volumetric demand for air varies in accordance with the requirements thereof. If desired, the flapper of the valve 31 may be perforated, as at '33, in order to prevent fluttering of said flapper when the pressure at the opposite sides thereof are nearly bal n e .I claim:

1- A blower of the centrifug l typ including a cylindrical casing having a series of compression chambers and impellers therein for moving air through said compression chambers, a motor for driving said impellers, an axial inlet leading into the first of the compression chamber in the seri n tle in each of the compression chambers leading into the next compression chamber in said series, a plurality of said compression chambers with the impellers therein providing a primary stage in said blower, a first oulet in the casing leading from the last compression chamber in said primary stage at the high pressure end thereof, a compression chamher with an impeller therein added to those of the primary stage and providing a booster stage in said blower, a passage leading from the said last compression chamber in the primary stage into the said booster stage,

a second outlet in said casing leading from the said booster stage, a common outlet pipe extending from said casing and encompassing both of said first and second outlets, a partition between said first and second outlets extending into said outlet pipe for a portion of its length, and a valve including a flapper pivotally mounted upon said partition adjacent the top thereof and responsive to variations in the pressure of air flowing through said outlet pipe from the second outlet to control the flow of air through said outlet pipe from the first outlet.

2. A blower as set forth in claim 1 wherein the said flapper is normally biased towards the wall of said pipe and cooperating therewith for restricting the flow of air from the primary stage. 7

3. A centrifugal type air blower including a casing having a plurality of compression chambers in series and each with an impeller for moving air thcrethrough, the

said compression chambers being divided into separate stages to provide a primary stage and a booster stage, an inlet leading into said compression chambers, a first outlet in the casing leading from the booster stage and a second outlet in the casing leading from the primary stage, a single outlet pipe connected to said casing and encompassing both of said first and second outlets, a partition separating said outlets and extending from said casing into said outlet pipe, and a valve pivotally mounted upon said partition and responsive to variationsin air pressure in said outlet pipe to control the flow of air through the said first outlet.

Refer nces Cited in th file of is patent UNITED STATES PATENTS 

